Sunday, June 2, 2013

From SigAlerts to Tanker Fires: How Caltrans Manages Los Angeles Freeways


             Transportation management has a long history with the rise and sprawl of the Los Angeles freeway system. By the 1950’s, the number of vehicles on the Los Angeles freeways exceed capacity, creating traffic jams and delays across Southern California. As the number of vehicles increased, so did collisions. To manage these crashes, the Los Angeles Police Department (LAPD) developed a specialized radio receiver that collected and recorded collision information to broadcast to radio stations’ engineers through the receivers [1]. This became known as the “SigAlert”, which was named after Loyd "Sig" Sigmon who invented the system. SigAlert is still in use today and publicly available online via the real-time traffic maps.

Along with SigAlert, technology innovations ushered in a new era of traffic management. The construction of the first California Department of Transportation (Caltrans) Transportation Management Center (TMC) in 1971 focused on traffic operations for the Los Angeles, Santa Monica, San Diego, and Harbor freeways [2]. To respond to unique and dynamic traffic situations and incidents, the TMC used a combination of solutions including the now established SigAlert along with a 42-mile freeway surveillance loop, complete with loop detectors and ramp metering. This was considered a major milestone and significant puzzle piece in place for completing a fully-automated traffic management system [4].

             Traffic management in Los Angeles has come a long way from it’s humble beginnings as a LAPD call log. Today, Caltrans and the California Highway Patrol (CHP) are responsible for the management and operation of 42 freeways totaling 1,188 freeway miles in Los Angeles and Ventura counties.

LARTMC hub. Source: California Department of Transportation

             As the Los Angeles freeway network continues to evolve, the infrastructure required to monitor the system needs to develop with it. Built in 2007 at eye-popping price tag of $46 million dollars [4], the Los Angeles Regional Transportation Management Center (LARTMC) is a state-of-the-art operations center that monitors and reacts to any and all incidents that affects traffic operations in the massive, sprawling Los Angeles freeway network. The purpose of LARTMC is to foster better agency interaction between Caltrans and the CHP, while ensuring the safe and efficient flow of traffic across the Los Angeles network [3].

             LARTMC gathers real-time information from a variety of sources such as electronic sensors in the pavement, video cameras, earthquake monitors, motorist cellular calls, and commercial traffic reporters [3]. From managing everyday incidents like traffic collisions and nighttime construction to large incidents like the 2008 tanker fire which closed Interstate 5 south of Los Angeles, real-time information is critical for LARTMC to process and keep Los Angeles moving.
             Looking towards the future, Caltrans and the CHP have big plans for LARTMC. The two agencies are in the process of developing a Regional Integration of ITS Elements (RITS) system, essentially an information portal for sharing traffic speed data and other information [2]. RITS is expected to help Caltrans coordinate with the City of Los Angeles, Los Angeles Metro, and several other local agencies.

[1] "Sig Alert." Wikipedia
[2] Caltrans TMC Coordination. The William and Barbara Leonard University Transportation Center.
[3] Inside Seven - Caltrans, District 7
[4] California Department of Transportation Fact Sheet

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